This study will investigate the hypothesis that skeletal muscle fatty acid oxidation during exercise is altered in NIDDM. In addition to studies utilizing exercise in NIDDM, will be used to assess glucose and lipid oxidation, and percutaneous muscle biopsy will be obtained to assay CPT I activity and malonyl CoA content. These measurements will permit an evaluation of relative use of glucose and FFA by exercising muscle in normal subjects and diabetics.